Clad Material, Method for Manufacturing Said Clad Material, and Apparatus for Manufacturing Said Clad Material

ABSTRACT

A method for manufacturing a clad material in which a core material is cast and skin materials are pressure-bonded thereon aims to prevent deterioration of adhesiveness of the core material and the skin materials while keeping sufficient cooling rate of the core material, prevent thickness variation and/or breakage of the skin materials during the manufacturing process, and keep the surface property of the cooling rolls constant. The method for manufacturing a clad material ( 11 ) includes the steps of continuously supplying molten metal (M) into a gap between a pair of cooling rollers ( 2   a ) ( 2   b ) to cast a core material, and cladding skin materials ( 10   a ) ( 10   b ) on both surfaces of the core material with hot rolling by continuously supplying the skin materials on peripheral surfaces of the cooling rollers so that the skin materials prevent direct contact between the cooling rollers and the molten metal, wherein the skin materials are supplied so as to come into contact with the peripheral surfaces of the cooling rollers, and wherein a contact distance (L 1 ) from a contact starting point (P 1 ) where the skin material begins to come into contact with the cooling roller to a meeting point (P 2 ) where the skin material begins to come into contact with the molten metal is set to 100 times or more of a thickness (t 1 ) of the skin material.

Priority is claimed to Japanese Patent Application No. 2004-35186 filedon Feb. 12, 2004, and U.S. Provisional Application No. 60/545,530 filedon Feb. 19, 2004, the disclosure of which are incorporated by referencein their entireties.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is an application filed under 35 U.S.C.§111(a) claimingthe benefit pursuant to 35 U.S.C.§119(e)(1) of the filing date of U.S.Provisional Application No. 60/545,530 filed on Feb. 19, 2004, pursuantto 35 U.S.C.§111(b).

TECHNICAL FIELD

The present invention relates to a clad material with skin materialslaminated on both sides of a core material for giving, for example,brazing performance and corrosion resistance, especially, a cladmaterial excellent in high-temperature strength, a method formanufacturing such clad material, and an apparatus for manufacturingsuch clad material.

BACKGROUND ART

The following description sets forth the inventor's knowledge of relatedart and problems therein and should not be construed as an admission ofknowledge in the prior art.

In recent years, in accordance with reduction in size and weight andimprovement in performance of heat exchanges, the materials thereof arerequired to be thin in thickness and high in strength. Furthermore, forthe purpose of decreasing environmental burden, a request ofalternatives for chlorofluorocarbon has increased, and therefore arequest of heat exchangers using CO₂ as refrigerant has increased.Examples of such heat exchangers meeting the above demands include heatexchangers represented by radiators and heater cores, which use water asa principal component of refrigerant, heat exchangers represented bycondensers and evaporators, which use fleon gas as refrigerant, and heatexchangers represented by gas coolers (evaporators), which use CO₂ asrefrigerant.

As a component for use in these heat exchangers, a clad materialconsisting of an aluminum alloy core and an aluminum alloy skin materialwhich gives brazing performance and corrosion prevention performance tothe surface of the core and having sufficient strength even afterbrazing has been used. In a generally employed method for manufacturingsuch clad material, a pre-heated ingot is hot-rolled and then thesurface thereof is scraped to obtain a core material having a thicknessof 250 mm to 400 mm. The core material and a skin material having athickness of 10 to 100 mm are placed one on another and then temporarilyfixed with each other. Thereafter, the temporarily fixed members aresubjected to hot-rolling, cold-rolling and, if necessary, intermediateannealing.

As a material of the aforementioned aluminum alloy core material, thereis an Al—Mn series alloy plate improved in high temperature strength bymanufacturing under predetermined heat-treating conditions and rollingconditions. However, although these Al—Mn series alloy plates areexcellent in characteristics as elementary substance, they can givesimultaneously neither brazing performance nor corrosion preventionperformance (Japanese Unexamined Laid-open Patent Publication No.2000-104149 and Japanese Unexamined Laid-open Patent Publication No.2002-241910).

Moreover, as for the method for manufacturing a clad material, in placeof the aforementioned hot-rolling method, various methods utilizingcontinuous casting of core materials have been proposed (JapaneseUnexamined Laid-open Patent Publication No. H11-226699, JapaneseLaid-open Patent Publication No. H8-509265 and Japanese Laid-open PatentPublication No. 2002-248599).

Japanese Unexamined Laid-open Patent Publication No. H11-226699discloses a method for continuously manufacturing a clad material inwhich a skin material is pressure-bonded to a core material which isbeing sent out from a cast rolling mill with pressure-bonding rollsdisposed at the vicinity of the outlet side of the rolling mill. Alsodisclosed in FIGS. 11 e and 11 f of Japanese Laid-open PatentPublication No. H8-509265 is a method for continuously casting a corematerial and cladding of the core material and a skin material withpressure-bonding rolls disposed at the outlet side of the coolingrollers of the cast rolling mill.

On the other hand, disclosed in FIGS. 11 a, 11 b and 11 c of JapaneseLaid-open Patent Publication No. H8-509265 is a method for manufacturinga clad material in which casting of a core material and pressure-bondingof the core material and the skin material are simultaneously performedby supplying the skin material at the inlet side of molten alloy withcooling rollers of the cast rolling apparatus. Also disclosed inJapanese Laid-open Patent Publication No. 2002-248599 is a method forsupplying a skin material at the inlet side of cooling rollers forcasting a core material when manufacturing a clad material in which thewidth of the skin material is wider than that of the core material andthe skin material is embedded in the core material.

However, there were the following problems in the manufacturing methodof the aforementioned clad material.

That is, according to the method in which pressure-bonding of the skinmaterial to the core material is performed after the casting of the corematerial, since it is necessary to arrange a cast rolling mill and apressure-bonding roll, the equipment becomes complicated in structure,and the production rate is restricted by the continuous casting rate ofthe core material. Furthermore, deterioration of adhesiveness of theskin material due to a segregation layer containing oxide formed on thesurface at the time of continuous cast rolling and deterioration ofcorrosion characteristics at the interface cannot be suppressed.

On the other hand, according to the method for simultaneously performingthe casting of the core material and the pressure-bonding of the skinmaterial to the core material, since the position where the skinmaterial comes into contact with the molten metal (core material) at theinlet side of the cooling rollers becomes unstable, a part of the skinmaterial may melt, or even may be broken. Furthermore, according toJapanese Laid-open Patent Publication No. 2002-248599, since the widthof the core material is larger than that of the skin material andtherefore the molten metal partially comes into contact with the coolingrollers, the roll surface property changes, resulting in difficulty incontrolling the roll surface property for a long time.

The description herein of advantages and disadvantages of variousfeatures, embodiments, methods, and apparatus disclosed in otherpublications is in no way intended to limit the present invention.Indeed, certain features of the invention may be capable of overcomingcertain disadvantages, while still retaining some or all of thefeatures, embodiments, methods, and apparatus disclosed therein.

Other objects and advantages of the present invention will be apparentfrom the following preferred embodiments.

DISCLOSURE OF INVENTION

The preferred embodiments of the present invention have been developedin view of the above-mentioned and/or other problems in the related art.The preferred embodiments of the present invention can significantlyimprove upon existing methods and/or apparatuses.

The present invention was made in view of the aforementioned problems,and aims to provide a method for manufacturing a clad material capableof keeping the surface property of cooling rollers constant whilekeeping high cooling rate of a core material, restraining deteriorationof adhesiveness of a skin layer due to contamination of non-metallicinclusion such as an oxide film formed at the interface of the skinmaterial and the core material, and restraining occurrence of thicknessvariation of the skin material after the cladding and/or breakage of theskin material during the manufacturing process. Furthermore, the presentinvention also aims to provide a clad material manufactured by theaforementioned method and an apparatus for manufacturing a clad materialfor executing the aforementioned method.

The method for manufacturing a clad material according to the presentinvention has the following structures as recited in Items (1) to (11).

(1) A method for manufacturing a clad material, comprising the steps of:

continuously supplying molten metal into a gap between a pair of coolingrollers to cast a core material; and

cladding skin materials on both surfaces of the core material with hotrolling by continuously supplying the skin materials on peripheralsurfaces of the cooling rollers so that the skin materials preventdirect contact between the cooling rollers and the molten metal,

wherein the skin materials are supplied so as to come into contact withthe peripheral surfaces of the cooling rollers, and

wherein a contact distance (L1) from a contact starting point (P1) wherethe skin material begins to come into contact with the cooling roller toa meeting point (P2) where the skin material begins to come into contactwith the molten metal is set to 100 times or more of a thickness (t1) ofthe skin material.

(2) The method for manufacturing a clad material as recited in theaforementioned Item 1, wherein the core material and the skin materialare made of aluminum or its alloy.

(3) The method for manufacturing a clad material as recited in theaforementioned Item 1, wherein the thickness (t1) of the skin materialis 20 to 400 μm.

(4) The method for manufacturing a clad material as recited in theaforementioned Item 2, wherein at least one of the skin materials ismade of Al—Si series alloy.

(5) The method for manufacturing a clad material as recited in theaforementioned Item 4, wherein the Al—Si series alloy consistsessentially of

Si: 5 to 15 mass %,

Fe: 0.05 to 0.6 mass %,

Cu: 0.01 to 0.6 mass %,

Mn: 0.01 to 0.8 mass %,

Mg: 0.01 to 0.2 mass %,

Ti: 0.01 to 0.2 mass %, and

the balance being Al and inevitable impurities.

(6) The method for manufacturing a clad material as recited in theaforementioned Item 2, wherein at least one of the skin materials ismade of Al—Zn series alloy.

(7) The method for manufacturing a clad material as recited in theaforementioned Item 6, wherein the Al—Zn series alloy consistsessentially of

Si: 0.05 to 0.6 mass %,

Fe: 0.05 to 0.6 mass %,

Cu: 0.01 to 0.6 mass %,

Mn: 0.01 to 0.8 mass %,

Mg: 0.01 to 0.2 mass %,

Ti: 0.01 to 0.2 mass %,

Zn: 0.35 to 8.5 mass %, and

the balance being Al and inevitable impurities.

(8) The method for manufacturing a clad material as recited in theaforementioned Item 1, wherein a thickness (t2) of the skin materialafter hot roll cladding is 0.5 to 8 mm.

(9) The method for manufacturing a clad material as recited in theaforementioned Item 2, wherein the molten metal to become the corematerial consists essentially of

Si: 0.05 to 1.5 mass %,

Fe: 0.05 to 2 mass %,

Cu: 0.05 to 0.8 mass %,

Mn: 0.15 to 2.8 mass %,

at least one of elements selected from the group consisting of Cr: 0.03to 0.7 mass %, Mg: 0.01 to 0.2 mass %, Ti: 0.01 to 0.3 mass %, and Zn:0.01 to 1.5 mass %, and

the balance being Al and inevitable impurities.

(10) The method for manufacturing a clad material as recited in theaforementioned Item 9, wherein the molten metal further includes atleast one of elements selected from the group consisting of Zr: 0.15 to1.5 mass %, V: 0.03 to 1.5 mass %, and Sc: 0.02 to 0.5 mass %.

(11) The method for manufacturing a clad material as recited in any oneof the aforementioned Items 1 to 10, wherein cold rolling is performedafter the hot roll cladding.

A clad material according to the present invention has the followingstructures as recited in Items (12) to (15).

(12) A clad material in which skin materials are clad on both surfacesof a core material, wherein the clad material is manufactured by thesteps of continuously supplying molten metal into a gap between a pairof cooling rollers to cast a core material, and cladding skin materialson both surfaces of the core material with hot rolling by continuouslysupplying the skin materials on peripheral surfaces of the coolingrollers so that the skin materials prevent direct contact between thecooling rollers and the molten metal, wherein the skin materials aresupplied so as to come into contact with the peripheral surfaces of thecooling rollers, and wherein a contact distance (L1) from a contactstarting point (P1) where the skin material begins to come into contactwith the cooling roller to a meeting point (P2) where the skin materialbegins to come into contact with the molten metal is set to 100 times ormore of a thickness (t1) of the skin material.

(13) The clad material as recited in the aforementioned Item 12, whereinthe clad material is cold rolled after the hot roll cladding.

(14) The clad material as recited in the aforementioned Item 12, whereinan average dendrite secondary arm spacing of the core material formed bythe heat roll cladding is 0.1 to 10 μm.

(15) The clad material as recited in any one of the aforementioned Items12 to 14, wherein the clad material is heat exchanger componentmaterial.

The apparatus for manufacturing a clad material according to the presentinvention has the following structures as recited in Item (16).

(16) An apparatus for manufacturing a clad material, comprising:

a pair of cooling rollers for continuously casting molten metal passingthrough a gap formed between the cooling rollers;

a molten metal supplying portion for supplying the molten metal tobecome a core material into the gap; and

a skin material supplying portion for supplying a skin material on aperipheral surface of the cooling roller and making the skin materialcome into contact with the peripheral surface of the cooling rollerbefore the skin material joins the molten metal,

wherein the cooling rolls are rotated while continuously supplying themolten metal and the skin material to the cooling rolls to therebycontinuously clad the skin materials to both surfaces of the corematerial.

EFFECTS OF THE INVENTION

According to the manufacturing method of the clad material of theinvention as recited in the aforementioned Item (1), since the skinmaterials are joined to the molten metal in a state in which the skinmaterial is cooled, the molten metal is solidified quickly by beingcooled by the cooling rollers. Therefore, a core material having highhardness can be cast and the skin materials can be pressure-bonded toboth surfaces of the core material. Since the skin material is cooled inadvance, melting and/or fusing of the skin material due to the heat ofthe molten metal M can be prevented, and a clad material can bemanufactured efficiently without reducing the cooling rate of the corematerial. Moreover, since the aforementioned skin materials arepressure-bonded during the solidification process of the core material,high adhesion can be attained. Furthermore, since the cooling rollersand the molten metal are intercepted by the skin material, thealteration and deterioration of the roll surface property due toadhesion of the molten metal can be prevented.

According to the invention as recited in the aforementioned Item (2),the aforementioned clad material which consists of aluminum or its alloycan be manufactured.

According to the invention as recited in the aforementioned Item (3),tension control of the skin material can be performed smoothly, andsufficient cooling rate of the core material can be secured.

According to the invention as recited in the aforementioned Item (4), analuminum brazing clad material with brazing material clad on the surfacecan be manufactured.

According to the invention as recited in the aforementioned Item (5),the aluminum brazing clad material excellent in especially brazingperformance can be manufactured.

According to the invention as recited in the aforementioned Item (6),the aluminum brazing clad material excellent in corrosion resistance inwhich a sacrificial corrosion layer is formed on the surface can bemanufactured.

According to the invention as recited in the aforementioned Item (7),the aluminum brazing clad material excellent in especially corrosionresistance can be manufactured.

According to the invention as recited in the aforementioned Item (8),molten metal can be supplied stably and it is possible to secure theheat releasing capacity from the cooling rollers.

According to the invention as recited in the aforementioned Item (9), analuminum brazing clad material excellent in strength even at hightemperature and excellent in corrosion resistance can be manufactured.

According to the invention as recited in the aforementioned Item (10),the aluminum material excellent in especially high temperature strengthcan be manufactured.

According to the invention as recited in the aforementioned Item (11),the clad material having a prescribed thickness can be manufactured.

The clad material according to the invention as recited in theaforementioned Item (12) is excellent in adhesiveness property betweenthe skin materials and the core material, or is a useful clad materialto which various characteristics, such as brazing performance, corrosionresistance and strength, are further added. Furthermore, the cladmaterial is excellent in workability.

According to the invention as recited in the aforementioned Item (13), aclad material having a prescribed thickness can be obtained.

According to the invention as recited in the aforementioned Item (14), aclad material especially excellent in strength can be obtained.

According to the invention as recited in the aforementioned Item (15),the clad material is useful as a heat exchanger structure componentmaterial.

According to the manufacturing apparatus of a clad material of theinvention as recited in the aforementioned Item (16), the manufacturingmethod of the present invention is executed and a clad material can bemanufactured efficiently.

The above and/or other aspects, features and/or advantages of variousembodiments will be further appreciated in view of the followingdescription in conjunction with the accompanying figures. Variousembodiments can include and/or exclude different aspects, featuresand/or advantages where applicable. In addition, various embodiments cancombine one or more aspect or feature of other embodiments whereapplicable. The descriptions of aspects, features and/or advantages ofparticular embodiments should not be construed as limiting otherembodiments or the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view showing an apparatus structure for executinga method for manufacturing a clad material according to the presentinvention.

FIG. 2 is a perspective view showing a brazed article used in a brazingtest.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following paragraphs, some preferred embodiments of the inventionwill be described by way of example and not limitation. It should beunderstood based on this disclosure that various other modifications canbe made by those in the art based on these illustrated embodiments.

A method for manufacturing a clad material according to a preferableembodiment of the present invention will be described in detail withreference to the clad material manufacturing apparatus 1 shown in FIG.1.

In FIG. 1, the reference numeral 2 a and 2 b denote a pair of coolingrollers disposed at a certain distance, the reference numeral 3 denotesa nozzle which injects molten metal M supplied from a molten-metalpreparation portion, such as a melting furnace and a tundish (notshown), into the gap between the aforementioned cooling rollers 2 a and2 b. The aforementioned nozzle 3 sets the meeting point P2 of the moltenmetal M and the skin material 10 a and 10 b by the opening width and theset position. The aforementioned nozzle 3 demonstrates effective rolesfor preventing melt breakage of the skin material and holding the cladratio (skin material/core material/skin material) constant. Thereference numeral 4 a (4 b) denotes a holding roll for holding down theskin material 10 a (10 b) continuously supplied by unwinding the skinmaterial coil (not shown) toward the cooling roller 2 a (2 b). Byadjusting the holding position of the holding roll 4 a (4 b), thecontact starting point P1 where the skin material 10 a (10 b) begins tocome into contact with the cooling roller 2 a (2 b) is set. Thereference numeral 11 denotes a plate-shaped core material made of castmolten metal M, and the reference numeral 12 denotes a three-layeredclad material in which the skin materials 10 a and 10 b are clad on bothsurfaces of the aforementioned core material 11.

In the manufacturing method of the clad material according to thepresent invention, when supplying the skin material 10 a (10 b) to thecooling roller 2 a (2 b), the skin material 10 a (10 b) is cooled bycoming into contact with the peripheral surface of the cooling roller 2a (2 b) before joining the molten metal M, and therefore the skinmaterial 10 a (10 b) joins the molten metal M in a cooled state. Forthis reason, the molten metal M supplied to the gap between the coolingrollers 2 a and 2 b is quickly solidified by being cooled by the coolingroller 2 a (2 b) even via the skin material 10 a (10 b), and the skinmaterial 10 a (10 b) is pressure-bonded and clad on both surfaces of thecore material 11. Furthermore, since the skin material 10 a (10 b) is tobe pressure-bonded to the core material 11 during the solidificationprocess of the core material 11, contamination, such as an oxide film,to the interface between the skin material 10 a (10 b) and the corematerial 11 can be prevented, resulting in excellent adhesiveness of theskin material 10 a (10 b) to the core material 11. Since theaforementioned skin material 10 a (10 b) is cooled beforehand, themelting and fusing of the skin material due to the heat of the moltenmetal M can be prevented, and therefore the clad material 12 can bemanufactured efficiently without reducing the cooling rate of the corematerial 11. Moreover, since the molten metal M and the cooling roller 2a (2 b) are intercepted by the aforementioned skin material 10 a (10 b),alteration and/or deterioration of the roll surface property due to theadhesion of the molten metal M can be prevented.

The contact distance L1 of the skin material 10 a (10 b) along which theaforementioned skin material 10 a(10 b) is pre-cooled by the coolingroller (2 a) 2 b, namely, the distance from the contact starting pointP1 where the skin material 10 a (10 b) comes into contact with thecooling roller 2 a (2 b) to the meeting point P2 where the skin material10 a (10 b) comes into contact with the molten metal M, it is necessaryto set such that the contact distance L1 is set to a length of 100 timesor more of the thickness t1 of the skin material 10 a (10 b) in order tofully cool the skin material 10 a (10 b) and to acquire theaforementioned effects. More preferably, the contact distance L1 is setto a length of 200 times to 100,000 times of the thickness t1 of theskin material 10 a (10 b).

It is possible to attain the aforementioned manufacturing conditions bysetting the contact distance L1 so that the ratio of the contactdistance to the thickness of the skin material (L1/t1) falls within theaforementioned range. For example, by changing the diameter of thecooling rollers 2 a (2 b) and the contact starting point P1 where theskin material 10 a (10 b) begins to come into contact with the coolingroller 2 a (2 b) so as to meet the aforementioned range, the range ofthe roller with which the skin material 10 a (10 b) is in contact,namely, the contact distance L1, can be adjusted. In cases where thecontact distance L1 is represented by a center angle as seen from thecenter of the cooling roller 2 a (2 b), it is preferable to adjust therange of the center angle so as to fall within the range of from 10 to270°. If it falls within this range, it becomes easy to arrange thedevices, and the skin material can be stably wound on the cooling roller2 a(2 b). It is more preferable to adjust the range so as to fall withinthe range of from 150 to 180°.

It is preferable that the thickness t1 of the aforementioned skinmaterial 10 a (10 b) is 20 to 400 μm. If it is less than 20 μm, itbecomes difficult to control the tension of the unwinding roll, which inturn makes it difficult to perform continuation operation due to thepossible breakage of the skin material. On the other hand, if it exceeds400 μm, the heat capacity of the skin material 10 a (10 b) increases.Therefore, the heat releasing capacity of the cooling roller 2 a (2 b)becomes insufficient, resulting in insufficient cooling rate. Thepreferable thickness t1 of the skin material 10 a (10 b) is 20 to 200μm. The thickness of the skin material 10 a (10 b) is not required to bethe same in both sides, and the skin materials different in thicknesscan be employed. Accordingly, the contact distances L1 of both skinmaterials can also be different with each other.

The thickness t2 of the core material 11 after the hot cladding ispreferably 0.5 to 8 mm. Since the present invention employs continuouscasting using a pair of cooling rollers 2 a and 2 b, if the platethickness t2 after the cladding is less than 0.5 mm, the roll gap is toonarrow to stably supply molten metal M. On the other hand, if thethickness exceeds 8 mm, the heat releasing capacity through the coolingroller 2 a (2 b) becomes insufficient, which makes it difficult tosecure sufficient cooling rate of the core material. The preferablethickness t2 of the core material 11 is 0.8 to 6 mm.

As will be understood from the above, it is possible to cast a corematerial 11 excellent in high-temperature strength and efficientlymanufacture a three-layered structural clad material 12 with skinmaterials 10 a and 10 b clad on both surfaces of the core material 11.

As for the aforementioned cooling rollers, the number of revolutions ofthe cooling rollers, and the materials of the cooling rollers, it ispossible to employ conventionally known ones, provided that coolingconditions of materials are sufficiently met under the aforementionedL1/t1 condition. For example, the diameter of the roller is preferably100 to 1,000 mm since such a cooling roll can be easily manufactured orobtained and therefore the entire apparatus can be constituted at lowercost. Furthermore, the number of revolutions of the cooling roller ispreferably 1 to 200 m/min., more preferably 5 to 150 m/min. incircumferential velocity. As the materials of the cooling rollers,aluminum or its alloy, copper or its alloy, and iron or its alloy can beexemplified.

In the aforementioned clad material 12, the materials of the corematerial 11 and the skin material 10 a and 10 b are metal, and aluminumand its alloy can be exemplified as such metal. The clad material madeof aluminum or its alloy can be used as component material whichconstitutes, for example, fluid passages, tubes, heat releasing fins ofheat exchangers.

As the core material and the skin material made of aluminum or itsalloy, the following material can be recommended.

As for the skin material, it is preferable to use Al—Si series alloywhich functions as brazing material and Al—Zn series alloy which givescorrosion resistance.

As the aforementioned Al—Si series alloy, it is preferable to use alloyconsisting of Si: 5 to 15 mass %, Fe: 0.05 to 0.6 mass %, Cu: 0.01 to0.6 mass %, Mn: 0.01 to 0.8 mass %, Mg: 0.01 to 0.2 mass %, Ti: 0.01 to0.2 mass %, and the balance being Al and inevitable impurities.

The reasons of adding each element in the aforementioned Al—Si seriesalloy are as follows.

Si is an element which makes the alloy function as brazing material bylowering the melting point of the alloy. The preferable Si content is6.5 to 11 mass %. Fe is an element to be added to improve thewettability of brazing material, and if the content is less than 0.05mass %, the effects will become poor. To the contrary, if it exceeds 0.6mass %, large and rough intermetallic compound will be generated, whichgives adverse effects on corrosion resistance. The preferable Fe contentis 0.1 to 0.5 mass %. Cu is an element to be added to control theelectric potential of the skin material (Al—Si series alloy). Forexample, in cases where the clad material 12 is used as a brazing tubeof a heat exchanger, the electric potential of the brazing materialbecomes unnecessarily less noble with respect to the tube. Therefore, Cuis added to restrain an occurrence of preferential corrosion of fillets.The preferable Cu content is 0.02 to 0.5 mass %. Mn is an element to beadded to control the electric potential of the brazing material like Cu.If the content exceeds 0.8 mass %, the flowing characteristics of thebrazing material may be inhibited. The preferable Mn content is 0.02 to0.6 mass %. Mg is an element to be added to improve the strength. If itis less than 0.01 mass %, the effects become poor. To the contrary, itexceeds 0.2 mass %, the brazing performance will be inhibitedremarkably. The preferable Mg content is 0.01 to 0.1 mass %. Ti is anelement to be added to control the electric potential of the brazingmaterial. The preferable Ti content is 0.01 to 0.1 mass %.

As the aforementioned Al—Zn series alloy, it is preferable to use analloy consisting of Si: 0.05 to 0.6 mass %, Fe: 0.05 to 0.6 mass %, Cu:0.01 to 0.6 mass %, Mn: 0.01 to 0.8 mass %, Mg: 0.01 to 0.2 mass %, Ti:0.01 to 0.2 mass %, Zn: 0.35 to 8.5 mass %, and the balance being Al andinevitable impurities.

The reasons of adding each element in the aforementioned Al—Zn seriesalloy are as follows.

Zn is an element which is dissolved in Al to make the skin materialfunction as a sacrificial corrosion layer of the core material. Thepreferable Zn content is 0.35 to 6 mass %. Si is an element to be addedto improve the strength, and the preferable Si content is 0.1 to 0.5mass %. Although Fe is an element to be added to improve the strength,if it exceeds 0.6 mass %, large and rough intermetallic compounds willbe generated, which may cause a deterioration of corrosion resistance.The preferable Fe content is 0.1 to 0.5 mass %. Cu is an element to beadded to control the electric potential of the skin material. Thepreferable Cu content is 0.02 to 0.3 mass %. Mn is an element to beadded to control the electric potential of the skin material. Thepreferable Mn content is 0.02 to 0.6 mass %. Mg is an element to beadded to improve the strength. If it is less than 0.01 mass %, theeffects cannot be obtained. To the contrary, if it exceeds 0.2 mass %,the brazing performance may be remarkably inhibited. The preferable Mgcontent is 0.01 to 0.1 mass %. Ti is an element to be added to controlthe electric potential of the skin material. The preferable Ti contentis 0.01 to 0.1 mass %.

The skin material having the aforementioned composition can be clad onat least one surface of the core material. A skin material to be clad onthe other surface of the core material can be a skin material having acomposition the same as or different from that of the aforementionedskin material.

On the other hand, as the core material 11, i.e., the molten metal M, itis preferable to use alloy consisting of at least one of elementsselected from the group consisting of Si: 0.05 to 1.5 mass %, Fe: 0.05to 2 mass %, Cu: 0.05 to 0.8 mass %, Mn: 0.15 to 2.8 mass %, at leastone element selected from the group consisting of Cr: 0.03 to 0.7 mass%, Mg: 0.01 to 0.2 mass %, Ti: 0.01 to 0.3 mass % and Zn: 0.01 to 1.5mass %, and the balance being Al and inevitable impurities. Furthermore,in the composition of the aforementioned molten metal M, it ispreferable to further contain at least one element selected from thegroup consisting of Zr: 0.15 to 1.5 mass %, V: 0.03 to 1.5 mass %, andSc: 0.02 to 0.5 mass %.

The reasons of adding each element in the composition of theaforementioned core material are as follows.

Si is an element to be added to improve the strength, and the preferableSi content is 0.5 to 1.2 mass %. Fe is an element to be added to improvethe strength. If it exceeds 2 mass %, intermetallic compounds, such asan Al—Fe—Mn—Si series, will be generated, which may inhibit corrosionresistance. The preferable Fe content is 0.1 to 0.5 mass %. Cu is anelement to be added to control the electric potential, cause theelectric potential to be noble than the electric potential of the skinmaterial by adding Cu, and perform corrosion prevention of the corematerial. The preferable Cu content is 0.05 to 0.6 mass %. Mn is anelement to be added to improve the strength, especially to improve thestrength at high temperature. The preferable Mn content is 0.5 to 2.5mass %. Cr is an element to be added to improve the high temperaturestrength, and the preferable Cr content is 0.05 to 0.3 mass %. Mg is anelement which is dissolved in Al to improve the high temperaturestrength, and the preferable Mg content is 0.05 to 0.2 mass %. Ti makeselectric potential noble, and is an element to be added to change thecorrosion from pitting corrosion to layer corrosion, and the preferableTi content is 0.05 to 0.25 mass %. Zn is an element added to control theelectric potential, and the preferable Zn content is 0.1 to 1 mass %.

Zr, V, and Sc which are added arbitrarily are elements to be added forthe purpose of raising the recrystallizing temperature and raising thehigh temperature strength. The preferable Zr content is 0.15 to 0.8 mass%. The preferable V content is 0.1 to 1 mass %. The preferable Sccontent is 0.04 to 0.5 mass %. It is sufficient that at least one of Zr,V, and Sc is included. However, two or all of three elements can beincluded.

The clad material manufactured from the aluminum or aluminum alloymentioned above can be formed into a predetermined thickness by furthersubjecting it to cold rolling if necessary. Moreover, heat treatingafter the cladding or cold rolling can also be performed arbitrarily.

The clad material manufactured by the manufacturing method of thepresent invention is excellent in high-temperature strength due to therapid solidification of the core material. Furthermore, since thebreakage thereof at the time of machining seldom occurs, the cladmaterial can be a clad material excellent in workability. Especially inthe crystalline structure of the core material, the clad material whoseaverage dendrite secondary arm spacing (DAS) is 0.1 to 10 μm hashigh-temperature strength. The more preferable average dendritesecondary arm spacing is 0.1 to 8 μm. Furthermore, the skin material towhich brazing performance and corrosion prevention performance was givenby the skin material having the prescribed components can be preferablyused as a brazing material of heat exchanger components, such as a fluidpassage, a tube and a heat releasing fin, to be used in high temperatureenvironment. Especially, the skin material can be used as structuralcomponents of heat exchangers using CO₂ refrigerant that especiallyexcellent high temperature strength is required.

The manufacturing apparatus for clad material according to the presentinvention is not limited to the manufacturing apparatus 1 having thestructure shown in FIG. 1, but can employ various structures having thesame function.

The cooling roller in the manufacturing apparatus of the presentinvention corresponds to the cooling roller 2 a and 2 b of themanufacturing apparatus 1 of the illustrated embodiment. Similarly, themolten-metal supplying portion corresponds to a molten-metal preparationportion which is located outside the drawing and arranged in front ofthe nozzle 3. The skin material feeding portion corresponds to theaforementioned holding roll 4 a (4 b) and the tension roll for adjustingthe tension of the skin material coil located outside the drawing or thetension of the skin member, etc.

EXAMPLES

It should be understood that the following examples do not limit thescope of the invention.

Using the apparatus 1 for manufacturing the clad material as shown inFIG. 1 and explained above, the three-layered clad material 12 of thepresent invention was manufactured.

In each following Examples 1 to 3, as the alloy constituting a corematerial and a skin material, the aluminum alloys having the chemicalcomposition shown in Table 1 were used. TABLE 1 Alloy Chemicalcomposition (mass %), the balance being Al and inevitable impurities No.Si Fe Cu Mn Mg Cr Ni Zn Ti Zr V Sc (a) 0.10 0.25 0.02 0.01 0.01 <0.01<0.01 0.02 0.01 <0.01 <0.01 <0.01 (b) 0.08 0.20 0.02 0.01 0.01 <0.01<0.01 0.04 0.01 0.18 <0.01 <0.01 (c) 0.25 0.50 0.12 0.02 0.01 0.01 <0.010.04 0.05 <0.01 <0.01 <0.01 (d) 0.25 0.40 0.15 1.05 0.01 0.01 <0.01 0.050.02 <0.01 <0.01 <0.01 (e) 0.25 0.40 0.15 0.95 0.01 0.20 <0.01 0.05 0.050.18 <0.01 <0.01 (f) 7.85 0.65 0.07 0.04 0.02 0.01 <0.01 0.10 0.02 <0.01<0.01 <0.01 (g) 0.30 0.60 0.14 0.05 1.52 0.04 <0.01 0.15 0.05 <0.01<0.01 <0.01 (h) 0.20 0.35 0.07 0.07 2.25 0.24 <0.01 0.08 0.05 <0.01<0.01 <0.01 (i) 0.48 0.33 0.05 0.04 0.55 0.03 <0.01 0.04 0.03 <0.01<0.01 <0.01 (j) 0.20 0.42 0.05 0.04 0.03 <0.01 <0.01 1.15 0.10 <0.01<0.01 <0.01 (k) 0.30 0.45 1.65 0.25 2.55 0.22 <0.01 5.55 0.10 0.18 <0.01<0.01 (l) 0.25 0.40 0.18 1.05 0.01 0.01 <0.01 0.05 0.02 <0.01 <0.01<0.01 (m) 4.55 0.55 0.06 0.04 0.02 0.01 <0.01 2.20 0.02 <0.01 <0.01<0.01 (n) 8.85 0.65 0.07 0.04 0.02 0.01 <0.01 2.20 0.02 <0.01 <0.01<0.01 (o) 15.80 0.64 0.07 0.04 0.02 0.01 <0.01 2.20 0.02 <0.01 <0.01<0.01 (p) 0.20 0.42 0.05 0.04 0.03 <0.01 <0.01 0.15 0.10 <0.01 <0.01<0.01 (q) 0.20 0.42 0.05 0.04 0.03 <0.01 <0.01 2.55 0.10 <0.01 <0.01<0.01 (r) 0.20 0.42 0.05 0.04 0.03 <0.01 <0.01 10.50 0.10 <0.01 <0.01<0.01 (s) 0.30 0.38 0.05 1.05 0.01 0.01 <0.01 1.50 0.02 <0.01 <0.01<0.01 (t) 8.50 0.45 0.10 0.04 0.02 0.01 <0.01 1.50 0.04 <0.01 <0.01<0.01 (u) 0.60 0.40 0.35 0.05 0.10 0.05 <0.01 0.85 0.05 <0.01 <0.01<0.01 (v) 0.80 0.50 0.35 1.55 0.10 0.15 <0.01 0.80 0.18 <0.01 <0.01<0.01 (w) 1.10 0.60 0.35 1.55 0.10 0.25 <0.01 0.80 0.18 <0.01 <0.01<0.01 (x) 1.10 0.65 0.45 1.55 0.15 0.25 <0.01 0.80 0.18 0.25 <0.01 <0.01(y) 1.10 0.65 0.45 1.55 0.15 0.25 <0.01 0.80 0.18 <0.01 0.20 <0.01 (z)1.10 0.65 0.45 1.55 0.15 0.25 <0.01 0.80 0.18 <0.01 <0.01 0.25

Example 1

This Example 1 is an example about the stability of the skin materialand the structure of the core material by the heat cladding conditions.

As a skin material 10 a and 10 b, an ingot made of the alloys Nos. (a),(c), (f) and (j) shown in Table 1 and manufactured by a semi-continuouscasting method was subjected to hot rolling, intermediate annealing at370° C.×4 h, then cold rolling and intermediate annealing if needed, tothereby obtain a material having a thickness t1 of 0.20 mm.

As for the inventive examples Nos. 1 to 10 and the comparative examplesNos. 11 to 19, and 21 shown in Table 2, using the aforementioned cladmaterial manufacturing apparatus 1, a three-layered heat rolled cladmaterial 12 with the skin materials 10 a and 10 b clad on both surfacesof the core material 11 was manufactured.

In detail, in the state in which the skin materials 10 a and 10 b whosereference sign is shown in Table 2 were set and rotated with the skinmaterial 10 a and 10 b contacting the peripheral surface of the coolingrollers 2 a and 2 b, the molten metal M having the core materialcompositions (b), (d), (e), (g), (h), (i) and (k) shown in Table 2 waspoured from the above. At this time, the target thickness of the corematerial 11 after the heat roll cladding was set to 4.0 mm. Moreover,the contact distance L1 from the contact starting point P1 where theaforementioned skin material 10 a (10 b) begins to come into contactwith the cooling roller 2 a (2 b) to the meeting point P2 where the skinmaterial begins to come into contact with the molten metal M was set to100 or 150 times of the thickness t1 of skin material 10 a (10 b) in theInventive examples Nos. 1 to 10, and set to 50 or 80 times of thethickness t1 of the skin material 10 a (10 b) in the comparativeexamples Nos. 11 to 19, and 21. Although the pouring temperature of themolten metal M was different depending on the composition of the corematerial 11, in order to prevent dissolution of the skin material 10 a(10 b), it was set such that it became higher than the solidificationstart temperature by about 5 to about 30° C. Moreover, the peripheralspeed of the cooling roller 2 a (2 b) was set to 30 m/min.

About the manufactured three-layered clad materials 12, the skinmaterial breakage and the skin material melting ratio were evaluated bythe following standard, and the average dendrite secondary arm spacing(DAS) of the core material was also measured. These results are shown inTable 2.

(Skin Material Breakage)

In the case where there was a breakage during the manufacturing thethree-layered clad material 12 of 100 m length, it was noted as “yes,”and in the case where there was no breakage, it was noted as “no.” Askin material noted as “no” skin material breakage was evaluated as agood article.

(Skin Material Melting Rate)

The skin material melting rate was expressed by percentage obtained byperforming five-point sampling from the organization observation of thecross-section of the hot rolled clad plate and averaging the fivemaximum values of the molten portions of the skin material and thendividing the average value by the original thickness of the skinmaterial. Here, it was calculated under the assumption that there was noarea reduction of the skin material due to rolling. In the case wherethe skin material melting rate was 5% or less, it was evaluated as agood article.

(Average DAS)

An arbitrary length L parallel to the dendrite principal axis wasobtained as an average value by performing five point measurements atthe value by divided by the number N of the secondary arm which existstherein. In the case where the average DAS was 10 μm less was estimatedas a good article.

Subsequently, after cold rolling each hot rolled clad material 12 into athickness of 110 μm, heat treating of 600° C.×10 min. was performed.This heat treating was heat-treatment supposing brazing. As for theinventive example No. 6 and the comparative example No. 16, they weresubjected to heat treating of 170° C.×5 h. As for the inventive exampleNo. 9 and the comparative example No. 19, they were subjected to heattreating of 120° C.×3 h. The heat treatment was a post-aging treatmentintended to improve the strength of the core material.

About the clad material after the aforementioned cold rolling and heattreating, the tensile strength at ordinary temperature and the tensilestrength after holding at 180° C.×10 h were measured. These results areshown in Table 2.

On the other hand, as for the comparative example No. 20 shown in Table2, the core material had the composition (b) and the skin material hadthe composition (f) shown in Table 1. Initially, the ingot manufacturedby the semi-continuous casting method was subjected to pre-heating andhot rolling after cutting the surface portion. The skin material havinga thickness of 20 mm and the core material having a thickness of 400 mmafter the surface cutting of the ingot surface were hot rolled tothereby obtain a hot rolled plate having a total thickness of 5 mm.Furthermore, the hot rolled plate with a thickness of 5 mm wascold-rolled into a thickness of 110 μm, and then subjected to heattreatment of 600° C.×10 min.

The skin material breakage, skin material melting rate, and corematerial average DAS of the hot rolled plate was evaluated. The skinmaterial breakage and the skin material melting rate were evaluated bythe same method as in the aforementioned invention. The core materialaverage DAS was the value of the central portion of the ingot (400 mmthickness) having the composition (b) to be used as a core material.Moreover, as to the cold rolled plate with a thickness of 110 mm, thetensile strength after 10 hours holding at ordinary temperature and 180°C. was measured. These results are shown in Table 2. TABLE 2 Hot rolledclad material Cold rolling Clad Material composition (three layeredclad) Total thickness Heat treatment material Skin/core/ Thickness ofthe Targeted thickness of after the cold Heating Late aging No. skinskin t1 (mm) of the core (mm) L1/t1 rolling (μm) conditions conditionsInvention 1 (a)(b)(a) 0.20 4.0 100 110 600° C. × 10 min — 2 (c)(b)(c)0.20 4.0 100 110 — 3 (f)(d)(f) 0.20 4.0 100 110 — 4 (f)(e)(f) 0.20 4.0100 110 — 5 (j)(e)(j) 0.20 4.0 100 110 — 6 (f)(g)(f) 0.20 4.0 100 110170° C. × 5 h 7 (f)(h)(f) 0.20 4.0 100 110 — 8 (f)(i)(f) 0.20 4.0 100110 — 9 (f)(k)(f) 0.20 4.0 100 110 120° C. × 3 h 10 (a)(b)(a) 1.20 4.0150 110 — Comp. 11 (a)(b)(a) 0.20 4.0 50 110 600° C. × 10 min — 12(c)(b)(c) 0.20 4.0 50 110 — 13 (f)(d)(f) 0.20 4.0 50 110 — 14 (f)(e)(f)0.20 4.0 50 110 — 15 (j)(e)(j) 0.20 4.0 50 110 — 16 (f)(g)(f) 0.20 4.050 110 170° C. × 5 h 17 (f)(h)(f) 0.20 4.0 50 110 — 18 (f)(i)(f) 0.204.0 50 110 — 19 (f)(k)(f) 0.20 4.0 50 110 120° C. × 3 h 20 (f)(b)(f)20/400/200 mm, hot roll clad 110 — into total thickness of 5 mm 21(a)(b)(c) 0.20 4.0 80 110 — Clad Quality of heat rolled clad materialTensile strength material Skin Skin melting Core average Normal temp.180° C. No. breakage rate (%) DAS (μm) strength (MPa) strength (MPa)Invention 1 No <1 5.2 110 65 2 No <1 4.8 115 67 3 No 3 3.8 135 78 4 No 34.2 145 82 5 No <1 4.4 143 80 6 No 2 6.0 125 75 7 No 3 6.5 180 110 8 No3 6.2 210 170 9 No 3 5.5 480 210 10 No <1 4.9 111 66 Comp. 11 Yes 6 12.498 59 12 Yes 6 13.2 102 60 13 Yes 20 11.3 115 70 14 Yes 22 11.5 120 7215 Yes 7 12.0 118 69 16 Yes 14 16.3 120 72 17 Yes 12 14.9 175 104 18 Yes13 15.5 180 111 19 No 7 13.8 410 195 20 Yes 6 25.2 75 48 21 Yes 6 11.5110 60

From the result shown in Table 2, it was confirmed that in eachinvention manufactured by the method of the present invention the skinmaterial was not broken, there was very few melting of the skinmaterial, and it was stably manufactured. Moreover, in the manufacturedclad material, it was confirmed that the average DAS was 10 μm or less,and it was excellent in high temperature strength.

Example 2

This Example 2 is an example about brazing performance and corrosionresistance by the skin material components and the skin material.

As a skin material 10 a and 10 b, an ingot manufactured from the alloysNos. (m) to (r) in Table 1 by a semi-continuous casting method wassubjected to hot rolling, intermediate annealing at 370° C.×4 h, thencold rolling and intermediate annealing if needed, to thereby obtain amaterial having a thickness t1 of 0.35 mm.

About the inventive examples Nos. 22 to 29 shown in Table 3, using thealloy having the composition shown in Table 1 as molten metal M to beused as a core material, a three-layered clad material 12 in which skinmaterials 10 a and 10 b were pressure-bonded to the both surfaces of thecore material 11 using the aforementioned apparatus 1 for manufacturinga clad material according to the example 1 was manufactured. Inmanufacturing, the target thickness of the core material 11 after thehot roll cladding was set to 5.0 mm. The contact distance L1 from thecontact starting point P1 to the cooling roller 2 a (2 b) of theaforementioned skin material 10 a (10 b) to the meeting point P2 wherethe skin material comes into contact with the molten metal M was set to200 times of the thickness t1 of skin material 10 a (10 b). Theremaining conditions were set to the same as in Example 1.

Subsequently, each heat rolled clad material 12 was cold-rolled into athickness of 110 μm, and then subjected to a heat treatment of 600°C.×10 min.

About the clad material after the cold rolling and heat treatment, thetensile strength at ordinary temperature, the tensile strength after180° C.×10 h holding, breakage of the skin material, melting rate of theskin material, the quality of hot rolled clad material with an averageDAS were measured or evaluated. These results are shown in Table 3.

Moreover, as to the cold-rolled three-layered clad material 12, thebrazing performance and the corrosion resistance were evaluated by thefollowing method.

(Brazing Performance)

As to the inventive examples No. 22, 24, 25, 28 and 29 using (m), (n),and (o) as a skin material, using the aluminum alloy having thecomposition (s) shown in Table 1, it was rolled into a sheet having athickness of 80 μm and processed into the fin 20 shown in FIG. 2.Moreover, as to the inventive examples Nos. 23, 26 and 27 using (p), (q)and (r) as a skin material, a three-layered clad material (5 μm/70 μm/5μm, the total thickness of 80 μm) having compositions (n), (s) and (n)shown in Table 1 was manufactured, and then processed into the fin 20shown in FIG. 2 in the same manner as mentioned above. Each of theaforementioned fins (20) had a fin thickness (Ft): 80 μm, a fin pitch(Fp): 2.0 mm and a fin height (Fh): 8 mm.

And as shown in FIG. 2, fins 20 and 20 were attached to both surfaces ofthe aforementioned three-layered clad material 12, and flux was appliedthereto. Then, they were subjected to a brazing test by heating at 600°C.×10 min.

About these brazed articles, the junction rate and erosion wereinvestigated. In the evaluation of the junction rate, the length thatthe fin 20 was detached was measured by cutting the fin, and calculatedby the following formula: [1−(fin detached length)/(the entire finjoining portion)]×100. In the case where the calculated result was 80%or more, it was shown as “∘.” In the case where the calculated resultwas less than 80%, it was shown as “x.” In the erosion valuation, incases where the erosion depth was less than 20 μm, it was shown as “∘,”and in cases where the erosion depth exceeded 20 μm, it was shown as“x.”

(Corrosion Resistance)

A brazed article constituted by the three-layered clad material 12 andfin 20 subjected to the brazing test was subjected to SWAAT Test(Synthetic sea Water Acetic Acid salt spray Test) defined in ASTM-G85-A3to investigate generation of apertures and fin detaching performances.The test conditions were as follows. Corrosion test liquid adjusted soas to be pH3 by adding acetic acid to artificial seawater according toASTM D1141 was used. A cycle of spraying the corrosion test liquidagainst the article for 0.5 hours and holding the article for 1.5 hoursunder the wet condition was repeated for 960 hours.

In evaluating the generation of pitting corrosion, in cases where nothrough-hole was formed in the clad material 12 after 960 hours, it wasnoted as “∘,” and in cases where through-holes were formed, it was notedas “x.” In evaluating the fin detachment, the sample fin subjected tothe corrosion test was cut, and the similar evaluation as in the jointrate was performed. As a result, in cases where the rate was 80% ormore, it was noted as “∘,” and in cases where the rate was less than80%, it was noted “x.” TABLE 3 Hot rolled clad material Materialcomposition (three layered clad) Cold rolling Clad Targeted Totalthickness Tensile strength material Thickness of the thickness of ofafter the cold Heat treatment Normal temp. 180° C. No. Skin/core/skinskin t1 (mm) the core (mm) L1/t1 rolling (μm) Heating conditionsstrength (MPa) strength (MPa) Invention 22 (n)(l)(n) 0.35 5.0 200 110600° C. × 10 min 140 80 23 (q)(l)(q) 0.35 5.0 200 110 135 78 24(m)(l)(m) 0.35 5.0 200 110 137 78 25 (o)(l)(o) 0.35 5.0 200 110 142 8326 (p)(l)(p) 0.35 5.0 200 110 130 78 27 (r)(l)(r) 0.35 5.0 200 110 13582 28 (n)(l)(n) 0.01 5.0 200 110 140 80 29 (n)(l)(n) 0.50 5.0 200 110130 77 Clad Brazing performance Corrosion resistance Quality of hotrolled clad material material Joining Generation Fin Breakage of Meltingrate of Average DAS of No. rate Erosion of aperatures detachment skinmaterial skin material (%) skin material (μm) Invention 22 ∘ ∘ ∘ ∘ No <14.0 23 ∘ ∘ ∘ ∘ No <1 4.4 24 x ∘ ∘ ∘ No <1 4.2 25 ∘ x ∘ ∘ No <1 3.8 26 ∘∘ x ∘ No <1 4.6 27 ∘ ∘ ∘ x No <1 4.8 28 ∘ ∘ ∘ ∘ No <1 3.6 29 ∘ ∘ ∘ ∘ No<1 5.0

From the result shown in Table 3, it was confirmed that by using thealuminum alloy of the predetermined composition as a skin materialoutstanding brazing performance and corrosion resistance could beobtained. It was further confirmed that breakage of the skin material,melting rate of the skin material and average DAS of the skin materialin each clad material were excellent.

Example 3

This example 3 is an example about an evaluation of the strength by thecore material composition.

As a skin material 10 a and 10 b, an ingot manufactured from the alloyNo. (t) in Table 1 by a semi-continuous casting method was subjected tohot rolling, intermediate annealing at 370° C.×4 h, then cold rollingand intermediate annealing if needed, to thereby obtain a materialhaving a thickness t1 of 0.25 mm.

About the inventive examples Nos. 30 to 35 shown in Table 4, using thealloys having compositions (u) to (z) shown in Table 1 as molten metal Mto be used as a core material, a three-layered clad material 12 in whichskin materials 10 a and 10 b were pressure-bonded to the both surfacesof the core material 11 using the aforementioned apparatus 1 formanufacturing a clad material according to the example 1 wasmanufactured. In manufacturing, the target thickness of the corematerial 11 after the hot roll cladding was set to 5.0 mm. The contactdistance L1 from the contact starting point P1 to the cooling roller 2 a(2 b) of the aforementioned skin material 10 a (10 b) to the meetingpoint P2 where the skin material comes into contact with the moltenmetal M was set to 200 times of the thickness t1 of skin material 10 a(10 b). The remaining conditions were set to the same as in Example 1.

Subsequently, each heat rolled clad material 12 was cold-rolled into athickness of 110 μm, and then subjected to a heat treatment of 600°C.×10 min.

About the clad material after the cold rolling and heat treatment, thetensile strength at ordinary temperature and the tensile strength after180° C.×10 h holding, the quality of the hot rolled clad material, thebrazing performance, and the corrosion resistance were measured. Theseresults are shown in Table 4. TABLE 4 Hot rolled clad material Materialcomposition (three layered clad) Cold rolling Clad Targeted Totalthickness Tensile strength material Thickness of the thickness of ofafter the cold Heat treatment Normal temp. 180° C. No. Skin/core/skinskin t1 (mm) the core (mm) L1/t1 rolling (μm) Heating conditionsstrength (MPa) strength (MPa) Invention 30 (t)(v)(t) 0.25 5.0 200 110600° C. × 10 min 87 53 31 (t)(w)(t) 0.25 5.0 200 110 92 58 32 (t)(x)(t)0.25 5.0 200 110 143 86 33 (t)(y)(t) 0.25 5.0 200 110 134 81 34(t)(z)(t) 0.25 5.0 200 110 152 92 35 (t)(u)(t) 0.25 5.0 200 110 65 38Clad Brazing performance Corrosion resistance Quality of hot rolled cladmaterial material Joining Generation Fin Breakage of Melting rate ofAverage DAS of No. rate Erosion of apertures detachment skin materialskin material (%) skin material (μm) Invention 30 ∘ ∘ ∘ ∘ No 2 3.8 31 ∘∘ ∘ ∘ No 2 4.0 32 ∘ ∘ ∘ ∘ No 3 4.2 33 ∘ ∘ ∘ ∘ No 3 4.8 34 ∘ ∘ ∘ ∘ No 34.4 35 ∘ ∘ ∘ ∘ No 2 3.8

From the result shown in Table 4, it was confirmed that by using thealuminum alloy of the predetermined composition as a core materialoutstanding high temperature strength could be obtained. Furthermore, itwas confirmed that the breakage of the skin material, the melting rateof the skin material, the average DAS of the core material, the brazingperformance and the corrosion resistance were excellent.

(Workability)

About each of the clad materials shown in Table 5 among the cladmaterials shown in Tables 2, 3 and 4, the workability was evaluatedbased on the formability when the clad material was formed by rollforming into a fin (20) shape as follows. In cases where it was formedinto a preferable shape, it was noted as “⊚”, in cases where it wasformed into a fin shape although there were variations in fin shapedimension, it was noted as “∘,” and in cases where it was impossible toform into a fin shape due to an occurrence of breakage, it was noted as“x”. TABLE 5 Clad material No. Workability Inventive article 1 ⊚ 4 ◯Comparative article 11 X 12 X Inventive article 22 ◯ 30 ⊚ 31 ⊚ 32 ◯ 33 ◯34 ◯ 35 ⊚

From the results shown in Table 5, it was confirmed that the cladmaterials according to the present invention was superior to thecomparative articles in workability. Furthermore, it was also confirmedthat the inventive articles not exhibited excellent tensile strength orbrazing performance in Tables 2 to 4 were superior to comparativearticles in workability.

In the above-mentioned Examples 1 to 3, the thickness t1 of the skinmaterial 10 a (10 b) was not changed while the skin materials 10 a and10 b were being clad onto the core material 11. However, the presentinvention is not limited to it. The present invention also includes thecase in which the thickness of the skin material decreases due to thecladding by receiving a slight rolling pressure together with the corematerial when the skin materials passes through the cooling rollers 2 aand 2 b.

INDUSTRIAL APPLICABILITY

The clad material manufactured by the present invention includes a corematerial and skin materials clad on the both surfaces of the corematerial, wherein the composition of the skin material is different fromthat of the core material. The clad material can be used formanufacturing metallic material to which the aforementionedcharacteristics were given by cladding brazing material or corrosionresistance material as skin material.

While the present invention may be embodied in many different forms, anumber of illustrative embodiments are described herein with theunderstanding that the present disclosure is to be considered asproviding examples of the principles of the invention and such examplesare not intended to limit the invention to preferred embodimentsdescribed herein and/or illustrated herein.

While illustrative embodiments of the invention have been describedherein, the present invention is not limited to the various preferredembodiments described herein, but includes any and all embodimentshaving equivalent elements, modifications, omissions, combinations(e.g., of aspects across various embodiments), adaptations and/oralterations as would be appreciated by those in the art based on thepresent disclosure. The limitations in the claims are to be interpretedbroadly based on the language employed in the claims and not limited toexamples described in the present specification or during theprosecution of the application, which examples are to be construed asnon-exclusive. For example, in the present disclosure, the term“preferably” is non-exclusive and means “preferably, but not limitedto.” In this disclosure and during the prosecution of this application,means-plus-function or step-plus-function limitations will only beemployed where for a specific claim limitation all of the followingconditions are present in that limitation: a) “means for” or “step for”is expressly recited; b) a corresponding function is expressly recited;and c) structure, material or acts that support that structure are notrecited. In this disclosure and during the prosecution of thisapplication, the terminology “present invention” or “invention” may beused as a reference to one or more aspect within the present disclosure.The language present invention or invention should not be improperlyinterpreted as an identification of criticality, should not beimproperly interpreted as applying across all aspects or embodiments(i.e., it should be understood that the present invention has a numberof aspects and embodiments), and should not be improperly interpreted aslimiting the scope of the application or claims. In this disclosure andduring the prosecution of this application, the terminology “embodiment”can be used to describe any aspect, feature, process or step, anycombination thereof, and/or any portion thereof, etc. In some examples,various embodiments may include overlapping features. In this disclosureand during the prosecution of this case, the following abbreviatedterminology may be employed: “e.g.” which means “for example;” and “NB”which means “note well.”

1. A method for manufacturing a clad material, comprising the steps of:continuously supplying molten metal into a gap between a pair of coolingrollers to cast a core material; and cladding skin materials on bothsurfaces of the core material with hot rolling by continuously supplyingthe skin materials on peripheral surfaces of the cooling rollers so thatthe skin materials prevent direct contact between the cooling rollersand the molten metal, wherein the skin materials are supplied so as tocome into contact with the peripheral surfaces of the cooling rollers,and wherein a contact distance (L1) from a contact starting point (P1)where the skin material begins to come into contact with the coolingroller to a meeting point (P2) where the skin material begins to comeinto contact with the molten metal is set to 100 times or more of athickness (t1) of the skin material.
 2. The method for manufacturing aclad material as recited in claim 1, wherein the core material and theskin material are made of aluminum or its alloy.
 3. The method formanufacturing a clad material as recited in claim 1, wherein thethickness (t1) of the skin material is 20 to 400 μm.
 4. The method formanufacturing a clad material as recited in claim 2, wherein at leastone of the skin materials is made of Al—Si series alloy.
 5. The methodfor manufacturing a clad material as recited in claim 4, wherein theAl—Si series alloy consists essentially of Si: 5 to 15 mass %, Fe: 0.05to 0.6 mass %, Cu: 0.01 to 0.6 mass %, Mn: 0.01 to 0.8 mass %, Mg: 0.01to 0.2 mass %, Ti: 0.01 to 0.2 mass %, and the balance being Al andinevitable impurities.
 6. The method for manufacturing a clad materialas recited in claim 2, wherein at least one of the skin materials ismade of Al—Zn series alloy.
 7. The method for manufacturing a cladmaterial as recited in claim 6, wherein the Al—Zn series alloy consistsessentially of Si: 0.05 to 0.6 mass %, Fe: 0.05 to 0.6 mass %, Cu: 0.01to 0.6 mass %, Mn: 0.01 to 0.8 mass %, Mg: 0.01 to 0.2 mass %, Ti: 0.01to 0.2 mass %, Zn: 0.35 to 8.5 mass %, and the balance being Al andinevitable impurities.
 8. The method for manufacturing a clad materialas recited in claim 1, wherein a thickness (t2) of the skin materialafter hot roll cladding is 0.5 to 8 mm.
 9. The method for manufacturinga clad material as recited in claim 2, wherein the molten metal tobecome the core material consists essentially of Si: 0.05 to 1.5 mass %,Fe: 0.05 to 2 mass %, Cu: 0.05 to 0.8 mass %, Mn: 0.15 to 2.8 mass %, atleast one of elements selected from the group consisting of Cr: 0.03 to0.7 mass %, Mg: 0.01 to 0.2 mass %, Ti: 0.01 to 0.3 mass %, and Zn: 0.01to 1.5 mass %, and the balance being Al and inevitable impurities. 10.The method for manufacturing a clad material as recited in claim 9,wherein the molten metal further includes at least one of elementsselected from the group consisting of Zr: 0.15 to 1.5 mass %, V: 0.03 to1.5 mass %, and Sc: 0.02 to 0.5 mass %.
 11. The method for manufacturinga clad material as recited in any one of claims 1 to 10, wherein coldrolling is performed after the hot roll cladding.
 12. A clad material inwhich skin materials are clad on both surfaces of a core material,wherein the clad material is manufactured by the steps of continuouslysupplying molten metal into a gap between a pair of cooling rollers tocast a core material, and cladding skin materials on both surfaces ofthe core material with hot rolling by continuously supplying the skinmaterials on peripheral surfaces of the cooling rollers so that the skinmaterials prevent direct contact between the cooling rollers and themolten metal, wherein the skin materials are supplied so as to come intocontact with the peripheral surfaces of the cooling rollers, and whereina contact distance (L1) from a contact starting point (P1) where theskin material begins to come into contact with the cooling roller to ameeting point (P2) where the skin material begins to come into contactwith the molten metal is set to 100 times or more of a thickness (t1) ofthe skin material.
 13. The clad material as recited in claim 12, whereinthe clad material is cold rolled after the hot roll cladding.
 14. Theclad material as recited in claim 12, wherein an average spacing of adendrite secondary arm spacing of the core material formed by the heatroll cladding is 0.1 to 10 μm
 15. The clad material as recited in anyone of claims 12 to 14, wherein the clad material is heat exchangercomponent material.
 16. An apparatus for manufacturing a clad material,comprising: a pair of cooling rollers for continuously casting moltenmetal passing through a gap formed between the cooling rollers; a moltenmetal supplying portion for supplying the molten metal to become a corematerial into the gap; and a skin material supplying portion forsupplying a skin material on a peripheral surface of the cooling rollerand making the skin material come into contact with the peripheralsurface of the cooling roller before the skin material joins the moltenmetal, wherein the cooling rolls are rotated while continuouslysupplying the molten metal and the skin material to the cooling rolls tothereby continuously clad the skin materials to both surfaces of thecore material.